Sort Directories by Size in Ksh

You can use -k to specify where in the input line the sort key starts and ends.

You use the -n option or add n to the sort key specification to trigger a numeric sort as opposed to a lexical sort by default. And -r to reverse the sort.

Here, for a numerical sort, you don't need to limit the sort key to the sort command. If you do:

sort -rn file

It will treat the whole line as a number. The 14 hjoeow; line for instance will be understood as the 14 number.

You could do:

sort -bk 1,1rn file

To sort on the first field only, but that would make no difference.

The command to join lines is paste with the -s option. You can specify the delimiter with -d. \0 is a special value for the delimiter that means join with nothing in between. So, to get your expected output:

sort -rn file | paste -sd '\0' -

POSIX paste require a filename be passed. - is again a special value that means standard input. You can omit it with some paste implementations.

ls does not directly support sorting by permissions, but you can combine it with the sort command:

ls -l | sort

You can use the -k option to sort to start matching from a specific character, the format is -k FIELD.CHAR, the permissions are the first field in the ls output. So e.g. -k 1.2 will start from the second character of the permission string, which will ignore any directory / device / link etc. flag, or -k 1.5 for sorting by group permissions.

If you don't want the additional output of ls -l, you can remove it with awk:

 ls -l | sort | awk '{ print $1, $NF}'

This will print only the first field (the permissions) and the last one (the filename).